A New Injectivity Prediction Model for Early Polymer Injection

Xiang’an Lu, Hanqiao Jiang, and Yanli Pei

Abstract—Early polymer injection has become an effective way to improve oil recovery in deep offshore fields. Since the reservoir will still be high in oil saturation during this process, a detailed description of water-oil two-phase flow is required to accurately predict polymer injectivity of the reservoir. A polymer fractional flow model was first derived by including polymer rheology effects and two phase flow resistance factor. Water saturation profile was then proposed as four self-sharpening fronts to describe the detailed fluid saturation distribution. The polymer injectivity prediction model for both monolayer and multilayer reservoirs was finally established by separating the pressure drop into several parts based on the saturation profile. Results showed the new model improved the accuracy and efficiency of injectivity prediction in early polymer injection. This model is more like a miniature numerical simulator for early polymer injection that can output the dynamic polymer injectivity with the input of only a few pieces of field data that can be acquired easily.